Clinical Implications of the Serum Apelin Level on Portal Hypertension and Prognosis of Liver Cirrhosis

Quercetin prevents rats from type 1 diabetic liver damage by inhibiting TGF-ꞵ/apelin gene expression

Background

Hyperglycemia-induced oxidative stress is a significant contributor to diabetic complications, including hepatopathy. The current survey aimed to evaluate the ameliorative effect of quercetin (Q) on liver functional disorders and tissue damage developed by diabetes mellitus in rats.

Methods

Grouping of 35 male Wistar rats was performed as follows: sham; sham + quercetin (sham + Q: quercetin, 50 mg/kg/day in 1 ml 1% DMSO for 6 weeks, by gavage); diabetic control (Diabetes: streptozotocin (STZ), 65 mg/kg, i.p.); diabetic + quercetin 1 (D + Q1: quercetin, 25 mg/kg/day in 1 ml 1% DMSO for 6 weeks, by gavage after STZ injection); and diabetic + quercetin 2 (D + Q2: quercetin, 50 mg/kg/day in 1 ml 1% DMSO for 6 weeks, by gavage after STZ injection). Body weight, food intake, and water intake were measured. Ultimately, the samples of plasma and urine, as well as tissue samples of the liver and pancreas were gathered for later assays.

Results

STZ injection ended in elevated plasma blood glucose levels, decreased plasma insulin levels, liver dysfunction (increased activity levels of AST, ALT, and ALP, increased plasma levels of total bilirubin, cholesterol, LDL, triglyceride, decreased plasma levels of total protein, albumin and HDL), enhanced levels of malondialdehyde, diminished activities of antioxidant enzymes (superoxide dismutase, and catalase), reduced level of glutathione (GSH) increased gene expression levels of apelin and TGF-ꞵ, plus liver histological destruction. All these changes were diminished by quercetin. However, the measure of improvement in the D + Q2 group was higher than that of the D + Q1 group.

Conclusions

Quercetin improved liver function after diabetes mellitus type 1, possibly due to reduced lipid peroxidation, increased antioxidant systems, and inhibiting the apelin/TGF-ꞵ signaling pathway.

Methods for assessing portal hypertension

Many researchers and clinicians have taken the value of hepatic venous pressure gradient (HVPG) as an essential prognostic factor in subjects with chronic liver diseases. HVPG ≥ 10 mmHg indicates the presence of clinically significant portal hypertension, the main predictor of the risk of variceal bleeding, hepatic decompensation, and mortality. However, HVPG measurement is invasive and requires high expertise, so its routine use outside tertiary care centers or clinical trials is limited. Clinically significant portal hypertension also might be detected using non-invasive options such as ultrasonography, elastography, magnetic resonance imaging, and indices derived from laboratory parameters. Our review aims to present the feasibility and applicability of HVPG in modern clinical practice in patients with liver cirrhosis, including invasive and non-invasive methods, based on literary sources from the MEDLINE database.

Bibliometric-analysis visualization and review of non-invasive methods for monitoring and managing the portal hypertension

Background

Portal hypertension monitoring is important throughout the natural course of cirrhosis. Hepatic venous pressure gradient (HVPG), regarded as the golden standard, is limited by invasiveness and technical difficulties. Portal hypertension is increasingly being assessed non-invasively, and hematological indices, imaging data, and statistical or computational models are studied to surrogate HVPG. This paper discusses the existing non-invasive methods based on measurement principles and reviews the methodological developments in the last 20 years.

Methods

First, we used VOSviewer to learn the architecture of this field. The publications about the non-invasive assessment of portal hypertension were retrieved from the Web of Science Core Collection (WoSCC). VOSviewer 1.6.17.0 was used to analyze and visualize these publications, including the annual trend, the study hotspots, the significant articles, authors, journals, and organizations in this field. Next, according to the cluster analysis result of the keywords, we further retrieved and classified the related studies to discuss.

Results

A total of 1,088 articles or review articles about our topic were retrieved from WoSCC. From 2000 to 2022, the number of publications is generally growing. “World Journal of Gastroenterology” published the most articles (n = 43), while “Journal of Hepatology” had the highest citations. “Liver fibrosis” published in 2005 was the most influential manuscript. Among the 20,558 cited references of 1,088 retrieved manuscripts, the most cited was a study on liver stiffness measurement from 2007. The highest-yielding country was the United States, followed by China and Italy. “Berzigotti, Annalisa” was the most prolific author and had the most cooperation partners. Four study directions emerged from the keyword clustering: (1) the evaluation based on fibrosis; (2) the evaluation based on hemodynamic factors; (3) the evaluation through elastography; and (4) the evaluation of variceal bleeding.

Conclusion

The non-invasive assessment of portal hypertension is mainly based on two principles: fibrosis and hemodynamics. Liver fibrosis is the major initiator of cirrhotic PH, while hemodynamic factors reflect secondary alteration of splanchnic blood flow. Blood tests, US (including DUS and CEUS), CT, and magnetic resonance imaging (MRI) support the non-invasive assessment of PH by providing both hemodynamic and fibrotic information. Elastography, mainly USE, is the most important method of PH monitoring.

Hepatic stellate cells in the injured liver: Perspectives beyond hepatic fibrosis

Over the last two decades, our understanding of the pathological role of hepatic stellate cells (HSCs) in fibrotic liver disease has increased dramatically. As HSCs are identified as the principal collagen-producing cells in the injured liver, several experimental and clinical studies have targeted HSCs to treat liver fibrosis. However, HSCs also play a critical role in developing nonfibrotic liver diseases such as cholestasis, portal hypertension, and hepatocellular carcinoma (HCC). Therefore, this review exclusively focuses on the role of activated HSCs beyond hepatic fibrosis. In cholestasis conditions, elevated bile salts and bile acids activate HSCs to secrete collagen and other extracellular matrix products, which cause biliary fibrosis and cholangitis. In the chronically injured liver, autocrine and paracrine signaling from liver sinusoidal endothelial cells activates HSCs to induce portal hypertension via endothelin-1 release. In the tumor microenvironment (TME), activated HSCs are the major source of cancer-associated fibroblasts (CAF). The crosstalk between activated HSC/CAF and tumor cells is associated with tumor cell proliferation, migration, metastasis, and chemoresistance. In TME, activated HSCs convert macrophages to tumor-associated macrophages and induce the differentiation of dendritic cells (DCs) and monocytes to regulatory DCs and myeloid-derived suppressor cells, respectively. This differentiation, in turn, increases T cells proliferation and induces their apoptosis leading to reduced immune surveillance in TME. Thus, HSCs activation in chronically injured liver is a critical process involved in the progression of cholestasis, portal hypertension, and liver cancer.

Noninvasive Detection of Clinically Significant Portal Hypertension in Compensated Advanced Chronic Liver Disease

Patients with compensated advanced chronic liver disease have different prognoses depending on the presence of portal hypertension. Current non-invasive diagnostic methods allow identification of clinically significant portal hypertension. Portosystemic collaterals on imaging or liver stiffness of more than 20 to 25 kPa by using transient elastography identifies patients with clinically significant portal hypertension. Patients with liver stiffness of less than 20 kPa and platelet count of greater than 150 g/L can avoid endoscopy. This rule could be expanded using spleen stiffness. Methods to risk stratify for portal hypertension in compensated advanced chronic liver disease and successfully treated chronic hepatitis C and B are subject of research.

Angiogenesis in the progression from liver fibrosis to cirrhosis and hepatocelluar carcinoma

Introduction: Persistent inflammation and hypoxia are strong stimulus for pathological angiogenesis and vascular remodeling, and are also the most important elements resulting in liver fibrosis. Sustained inflammatory process stimulates fibrosis to the end-point of cirrhosis and sinusoidal portal hypertension is an important feature of cirrhosis. Neovascularization plays a pivotal role in collateral circulation formation of portal vein, mesenteric congestion, and high perfusion. Imbalance of hepatic artery and portal vein blood flow leads to the increase of hepatic artery inflow, which is beneficial to the formation of nodules. Angiogenesis contributes to progression from liver fibrosis to cirrhosis and hepatocellular carcinoma (HCC) and anti-angiogenesis therapy can improve liver fibrosis, reduce portal pressure, and prolong overall survival of patients with HCC. Areas covers: This paper will try to address the difference of the morphological characteristics and mechanisms of neovascularization in the process from liver fibrosis to cirrhosis and HCC and further compare the different efficacy of anti-angiogenesis therapy in these three stages. Expert opinion: More in-depth understanding of the role of angiogenesis factors and the relationship between angiogenesis and other aspects of the pathogenesis and transformation may be the key to enabling future progress in the treatment of patients with liver fibrosis, cirrhosis, and HCC.

Plasma levels of apelin are reduced in patients with liver fibrosis and cirrhosis but are not correlated with circulating levels of bone morphogenetic protein 9 and 10

BACKGROUND

The peptide apelin is expressed in human healthy livers and is implicated in the development of hepatic fibrosis and cirrhosis. Mutations in the bone morphogenetic protein receptor type II (BMPR-II) result in reduced plasma levels of apelin in patients with heritable pulmonary arterial hypertension. Ligands for BMPR-II include bone morphogenetic protein 9 (BMP9), highly expressed in liver, and BMP10, expressed in heart and to a lesser extent liver. However, it is not known whether reductions in BMP9 and/or BMP10, with associated reduction in BMPR-II signalling, correlate with altered levels of apelin in patients with liver fibrosis and cirrhosis.

METHODS

Plasma from patients with liver fibrosis (n = 14), cirrhosis (n = 56), and healthy controls (n = 25) was solid-phase extracted using a method optimised for recovery of apelin, which was measured by ELISA.

RESULTS

Plasma apelin was significantly reduced in liver fibrosis (8.3 ± 1.2 pg/ml) and cirrhosis (6.5 ± 0.6 pg/ml) patients compared with controls (15.4 ± 2.0 pg/ml). There was no obvious relationship between apelin and BMP 9 or BMP10 previously measured in these patients. Within the cirrhotic group, there was no significant correlation between apelin levels and disease severity scores, age, sex, or treatment with β-blockers.

CONCLUSIONS

Apelin was significantly reduced in plasma of patients with both early (fibrosis) and late-stage (cirrhosis) liver disease. Fibrosis is more easily reversible and may represent a potential target for new therapeutic interventions. However, it remains unclear whether apelin signalling is detrimental in liver disease or is beneficial and therefore, whether an apelin antagonist or agonist have clinical use.

Endothelin-1 in portal hypertension: The intricate role of hepatic stellate cells

IMPACT STATEMENT

Portal hypertension is pathologically defined as increase of portal venous pressure, mainly due to chronic liver diseases such as fibrosis and cirrhosis. In fibrotic liver, activated hepatic stellate cells increase their contraction in response to endothelin-1 (ET-1) via autocrine and paracrine stimulation from liver sinusoidal endothelial cells and injured hepatocytes. Clinical studies are limited with ET receptor antagonists in cirrhotic patients with portal hypertension. Hence, studies are needed to find molecules that block ET-1 synthesis. Accumulation of extracellular matrix proteins in the perisinusoidal space, tissue contraction, and alteration in blood flow are prominent during portal hypertension. Therefore, novel matrix modulators should be tested experimentally as well as in clinical studies. Specifically, tumor necrosis factor-α, transforming growth factor-β1, Wnt, Notch, rho-associated protein kinase 1 signaling antagonists, and peroxisome proliferator-activated receptor α and γ, interferon-γ and sirtuin 1 agonists should be tested elaborately against cirrhosis patients with portal hypertension.

Are adropin, apelin, elabela, asprosin and betatrophin biomarkers for chronic hepatitis and staging of fibrosis?

Chronic viral hepatitis affects nearly one half billion people; it can result in hepatic fibrosis and cirrhosis if untreated. We investigated whether the polypeptides, adropin, apelin, elabela, asprosin and betatrophin, could be useful biomarkers for diagnosing chronic hepatitis and for the staging fibrosis. Patients 18-60 years old who underwent a liver biopsy for chronic hepatitis B (CHB) or C (CHC) from January 2014 to January 2019 were included in our study. The patients were divided into three groups: control group, CHB group, and CHC group. The CHB group comprised four subgroups based on the severity of the hepatic fibrosis. Liver biopsy specimens of all groups were evaluated for adropin, apelin, elabela, asprosin and betatrophin immunoreactivity by light microscopy. Adropin, apelin, elabela and betatrophin were immunoreactive in the hepatocytes, while asprosin was not in any group. In the CHB group, adropin and elabela immunoreactivity was increased significantly in stages III and IV patients compared to the other subgroups, whereas stages I and II patients were comparable to the control group. The CHC group exhibited decreased betatrophin immunoreactivity and increased elabela immunoreactivity compared to the control group. We suggest that adropin and elabela can provide clues for staging and monitoring fibrosis in CHB, and may be potentially useful biomarkers.

Roles of the Hepatic Endocannabinoid and Apelin Systems in the Pathogenesis of Liver Fibrosis

Hepatic fibrosis is the consequence of an unresolved wound healing process in response to chronic liver injury and involves multiple cell types and molecular mechanisms. The hepatic endocannabinoid and apelin systems are two signalling pathways with a substantial role in the liver fibrosis pathophysiology-both are upregulated in patients with advanced liver disease. Endogenous cannabinoids are lipid-signalling molecules derived from arachidonic acid involved in the pathogenesis of cardiovascular dysfunction, portal hypertension, liver fibrosis, and other processes associated with hepatic disease through their interactions with the CB₁ and CB₂ receptors. Apelin is a peptide that participates in cardiovascular and renal functions, inflammation, angiogenesis, and hepatic fibrosis through its interaction with the APJ receptor. The endocannabinoid and apelin systems are two of the multiple cell-signalling pathways involved in the transformation of quiescent hepatic stellate cells into myofibroblast like cells, the main matrix-producing cells in liver fibrosis. The mechanisms underlying the control of hepatic stellate cell activity are coincident despite the marked dissimilarities between the endocannabinoid and apelin signalling pathways. This review discusses the current understanding of the molecular and cellular mechanisms by which the hepatic endocannabinoid and apelin systems play a significant role in the pathophysiology of liver fibrosis.

Mechanism of KLF4 Protection against Acute Liver Injury via Inhibition of Apelin Signaling

Krüppel-like factor 4 (KLF4) is a key transcription factor that regulates genes involved in the proliferation or differentiation in different tissues. Apelin plays roles in cardiovascular functions, metabolic disease, and homeostatic disorder. However, the biological function of apelin in liver disease is still ongoing. In this study, we investigated the mechanism of KLF4-mediated protection against acute liver injury via the inhibition of the apelin signaling pathway. Mice were intraperitoneally injected with carbon tetrachloride (CCl₄; 0.2 mL dissolved in 100 mL olive oil, 10 mL/kg) to establish an acute liver injury model. A KLF4 expression plasmid was injected through the tail vein 48 h before CCl₄ treatment. In cultured LX-2 cells, pAd-KLF4 or siRNA KLF4 was overexpressed or knockdown, and the mRNA and protein levels of apelin were determined. The results showed that the apelin serum level in the CCl₄-injected group was higher than that of control group, and the expression of apelin in the liver tissues was elevated while KLF4 expression was decreased in the CCl₄-injected group compared to the KLF4-plasmid-injected group. HE staining revealed serious hepatocellular steatosis in the CCl₄-injected mice, and KLF4 alleviated this steatosis in the mice injected with KLF4 plasmid. In vitro experiments showed that tumor necrosis factor-alpha (TNF-α) could downregulate the transcription and translation levels of apelin in LX-2 cells and also upregulate KLF4 mRNA and protein expression. RT-PCR and Western blotting showed that the overexpression of KLF4 markedly decreased basal apelin expression, but knockdown of KLF4 restored apelin expression in TNF-α-treated LX-2 cells. These in vivo and in vitro experiments suggest that KLF4 plays a key role in inhibiting hepatocellular steatosis in acute liver injury, and that its mechanism might be the inhibition of the apelin signaling pathway.

Portal pressure monitoring-state-of-the-art and future perspective

Portal hypertension is a serious symptom of chronic liver diseases, which can lead to many critical complications, such as the formation of varices related to upper digestive bleeding, ascites, infection, hepatic encephalopathy, renal failure, and even death. As a result, portal pressure monitoring has important prognostic and clinical implications. The hepatic venous pressure gradient measurement, a gold-standard method applied to monitor portal pressure, is invasive and only available in experienced centers. Over the past decade, noninvasive methods aimed at monitoring the portal pressure have been increasingly investigated, including serum markers, radiological features, ultrasound elastography, doppler and contrast-enhanced ultrasonography. In this study, we focused on both invasive and noninvasive methods for portal pressure monitoring and explored their roles in clinical setting. The advantages and limitations of various techniques for future research are also discussed.

Plasma diamine oxidase level predicts 6-month readmission for patients with hepatitis B virus-related decompensated cirrhosis

BACKGROUND AND AIMS

Hepatitis B virus-related decompensated cirrhosis is difficult to cure but has a high readmission rate due to multiple complications. Our aim was to investigate the diagnostic potential value of plasma diamine oxidase (DAO) for 6-month readmission of patients with HBV-related decompensated cirrhosis.

METHODS

A total of 135 patients with HBV-related decompensated cirrhosis were prospectively collected at the onset of discharge of hospital, and then were followed up for at least 6 months with the readmission as the primary outcome. The plasma DAO level was measured using enzyme linked immunosorbent assay. In addition, 120 age and sex matched patients with HBV-related compensated cirrhosis were included as controls.

RESULTS

A total of 36 patients (36.7%) with decompensated cirrhosis admitted to hospital during the 6-month follow up. The plasma DAO level of readmission group [21.1 (14.5; 29.0) ng/ml] was significantly higher than that in the non-readmission group [12.7 (9.3; 18.0) ng/mL, P < 0.001]. Multivariate analysis showed that the plasma DAO level (HR = 1.102, P < 0.05) and hepatic encephalopathy (HE) (HR = 5.018, P < 0.05) were independent factors for 6-month readmission of decompensated cirrhosis. DAO level showed higher area under the curve of receiver operating characteristic (AUROC) than HE (0.769 vs. 0.598, P < 0.05) and Child-Pugh-Turcotte (CPT) score (0.769 vs. 0.652, P < 0.05) for predicting 6-month readmission rate, with the best cut-off value as 19.7 ng/mL. Furthermore, plasma DAO level (HR = 1.184, P < 0.05) was an independent factor and has the higher AUROC than CPT score for the onset of recurrent HE (0.905 vs. 0.738, P < 0.05) during the 6-month follow up.

CONCLUSIONS

Plasma DAO level > 19.7 ng/mL predicts high rate of 6-month readmission in patients with HBV-related decompensated cirrhosis.

Apelin promotes hepatic fibrosis through ERK signaling in LX-2 cells

Apelin participates in cardiovascular functions, metabolic disease, and homeostasis disorder. However, the biological function of apelin in liver diseases, especially liver fibrosis is still under investigation. The present study aimed to investigate the expression of apelin in nonalcoholic fatty liver disease (NAFLD) and the mechanism of apelin promoting hepatic fibrosis through ERK signaling in hepatic stellate LX-2 cells. The results showed that the ALT and AST levels in serum were increased in the mice fed HFC. The histological staining revealed that hepatocellular steatosis and ballooning degeneration was severe, and fibrogenesis appeared as increased pericellular collagen deposition along with pericentral (lobular) collagen deposition in the mice fed HFC. Immunochemistry and qRT-PCR results showed that the expression of apelin and profibrotic genes was higher as compared to the control group. The in vitro experiments demonstrated that apelin-13 upregulated the transcription and translation levels of collagen type I (collagen-I) and α-smooth muscle actin (α-SMA) in LX-2 cells. The immunofluorescent staining, qRT-PCR, and Western blot results showed that the overexpression of apelin markedly increased the expression of α-SMA and cyclinD1. The LX-2 cells treated with apelin-13 displayed an increased expression of pERK1/2 in a time-dependent manner, while the pretreatment with PD98059 abolished the apelin-induced expression of α-SMA and cyclinD1. Furthermore, the in vivo and in vitro assays suggested a key role of apelin in promoting liver fibrosis, and the underlying mechanism might be ascribed to the apelin expression of profibrotic genes via ERK signaling pathway.

Function and regulation of apelin/APJ system in digestive physiology and pathology

Apelin is an endogenous ligand of seven-transmembrane G-protein-coupled receptor APJ. Apelin and APJ are distributed in various tissues, including the heart, lung, liver, kidney, and gastrointestinal tract and even in tumor tissues. Studies show that apelin messenger RNA is widely expressed in gastrointestinal (GI) tissues, including stomach and small intestine, which is closely correlated with GI function. Thus, the apelin/APJ system may exert a broad range of activities in the digestive system. In this paper, we review the role of the apelin/APJ system in the digestive system in physiological conditions, such as gastric acid secretion, control of appetite and food intake, cell proliferation, cholecystokinin secretion and histamine release, gut-brain axis, GI motility, and others. In pathological conditions, the apelin/APJ system plays an important role in the healing process of stress gastric injury, the clinical features and prognosis of patients with gastric cancers, the reduction of inflammatory response to enteritis and pancreatitis, the mediation of liver fibrogenesis, the promotion of liver damage, the inhibition of liver regeneration, the contribution of splanchnic neovascularization in portal hypertension, the treatment of colon cancer, and GI oxidative damage. Overall, the apelin/APJ system plays diversified functions and regulatory roles in digestive physiology and pathology. Further exploration of the relationship between the apelin/APJ system and the digestive system will help to find new and effective drugs for treating and alleviating the pain of digestive diseases.

Impact of sarcopenia on prognostic value of cirrhosis: going beyond the hepatic venous pressure gradient and MELD score

BACKGROUND

Sarcopenia has been reported as a prognostic factor. We evaluated the impact of sarcopenia to the conventional prognostic factors [Model for End-Stage Liver Disease (MELD) score, Child-Turcotte-Pugh (CTP) score, hepatic venous pressure gradient (HVPG)] in cirrhosis.

METHODS

Overall, 452 patients with cirrhosis were stratified by MELD score (low < 15, high ≥ 15), CTP class, and HVPG [non-clinically significant portal hypertension (CSPH), 6-9 mmHg; CSPH, 10-19 mmHg; extremely severe PH, ≥20 mmHg]. L3 skeletal muscle index as marker of sarcopenia was subdivided into quartiles (47.01-52.25-58.22 cm2 /m2 ).

RESULTS

Among the patients, 42% (190/452) presented with sarcopenia. During a median follow-up period of 21.2 months, sarcopenia was associated with mortality (adjusted hazard ratio = 2.253, P < 0.001) and specifically with compensated and early decompensated stages of cirrhosis, but not with advanced decompensated stages; low (P < 0.001) and high (P = 0.095) MELD scores; CTP classes A (P = 0.034), B (P < 0.001), and C (P = 0.205); and non-CSPH (P = 0.018), CSPH (P < 0.001), and extremely severe PH (P = 0.846). In quartiles of sarcopenia, MELD score, CTP class, and HVPG were independent predictors of mortality in non-sarcopenia, but not in severe sarcopenia (MELD, P = 0.182; CTP, P = 0.187; HVPG, P = 0.077).

CONCLUSIONS

Sarcopenia is associated with mortality in compensated and early decompensated cirrhosis, and existing conventional prognostic factors had limited value in severe sarcopenia. Therefore, incorporating sarcopenia in the conventional prognostic factors had added value, particularly in compensated and early decompensated cirrhosis. Subclassification of prognostic factors according to sarcopenia may help to better assess the prognosis of cirrhosis.

Role of the renin-angiotensin system in hepatic fibrosis and portal hypertension

The renin-angiotensin system (RAS) is an important regulator of cirrhosis and portal hypertension. As hepatic fibrosis progresses, levels of the RAS components angiotensin (Ang) II, Ang-(1-7), angiotensin-converting enzyme (ACE), and Ang II type 1 receptor (AT1R) are increased. The primary effector Ang II regulates vasoconstriction, sodium homoeostasis, fibrosis, cell proliferation, and inflammation in various diseases, including liver cirrhosis, through the ACE/Ang II/AT1R axis in the classical RAS. The ACE2/Ang-(1-7)/Mas receptor and ACE2/Ang-(1-9)/AT2R axes make up the alternative RAS and promote vasodilation, antigrowth, proapoptotic, and anti-inflammatory effects; thus, countering the effects of the classical RAS axis to reduce hepatic fibrogenesis and portal hypertension. Patients with portal hypertension have been treated with RAS antagonists such as ACE inhibitors, Ang receptor blockers, and aldosterone antagonists, with very promising hemodynamic results. In this review, we examine the RAS, its roles in hepatic fibrosis and portal hypertension, and current therapeutic approaches based on the use of RAS antagonists in patients with portal hypertension.

Clinical value of liver and spleen shear wave velocity in predicting the prognosis of patients with portal hypertension

AIM

To explore the relationship of liver and spleen shear wave velocity in patients with liver cirrhosis combined with portal hypertension, and assess the value of liver and spleen shear wave velocity in predicting the prognosis of patients with portal hypertension.

METHODS

All 67 patients with liver cirrhosis diagnosed as portal hypertension by hepatic venous pressure gradient in our hospital from June 2014 to December 2014 were enrolled into this study. The baseline information of these patients was recorded. Furthermore, 67 patients were followed-up at 20 mo after treatment, and liver and spleen shear wave velocity were measured by acoustic radiation force impulse at the 1^st week, 3^rd month and 9^th month after treatment. Patients with favorable prognosis were assigned into the favorable prognosis group, while patients with unfavorable prognosis were assigned into the unfavorable prognosis group. The variation and difference in liver and spleen shear wave velocity in these two groups were analyzed by repeated measurement analysis of variance. Meanwhile, in order to evaluate the effect of liver and spleen shear wave velocity on the prognosis of patients with portal hypertension, Cox’s proportional hazard regression model analysis was applied. The ability of those factors in predicting the prognosis of patients with portal hypertension was calculated through receiver operating characteristic (ROC) curves.

RESULTS

The liver and spleen shear wave velocity in the favorable prognosis group revealed a clear decline, while those in the unfavorable prognosis group revealed an increasing tendency at different time points. Furthermore, liver and spleen shear wave velocity was higher in the unfavorable prognosis group, compared with the favorable prognosis group; the differences were statistically significant (P < 0.05). The prognosis of patients with portal hypertension was significantly affected by spleen hardness at the 3^rd month after treatment [relative risk (RR) = 3.481]. At the 9^th month after treatment, the prognosis was affected by liver hardness (RR = 5.241) and spleen hardness (RR = 7.829). The differences between these two groups were statistically significant (P < 0.05). The ROC analysis revealed that the area under the curve (AUC) of spleen hardness at the 3^rd month after treatment was 0.644, while the AUCs of liver and spleen hardness at the 9^th month were 0.579 and 0.776, respectively. These might predict the prognosis of patients with portal hypertension.

CONCLUSION

Spleen hardness at the 3^rd month and liver and spleen shear wave velocity at the 9^th month may be used to assess the prognosis of patients with portal hypertension. This is hoped to be used as an indicator of predicting the prognosis of patients with portal hypertension.

Apelin/APJ system: A key therapeutic target for liver disease

Apelin, a new bioactive peptide, was identified as an endogenous ligand for APJ (Angiotensin II receptor-like 1). Apelin and its receptor have an abundant distribution in central nervous system and peripheral tissues, including liver. Apelin/APJ has diverse physiological and pathological effects, including regulation of cardiovascular function, angiogenesis, fluid homeostasis and so on. Apelin/APJ system may act as a novel potential therapeutic target for liver disease. In this article, we review the role of apelin/APJ system in liver fibrosis, hepatitis, hepatic cirrhosis, liver injury and metabolic liver disease.

The Role of the Apelin/APJ System in the Regulation of Liver Disease

Apelin is an endogenous peptide that is a ligand for the APJ receptor (angiotensin II receptor like-1, AT-1). The apelin/APJ system is distributed in diverse periphery organ tissues. It has been shown that the apelin/APJ system plays various roles in physiology and pathophysiology of many organs. It regulates cardiovascular development or cardiac disease, glycometabolism and fat metabolism as well as metabolic disease. The apelin/APJ system participates in various cell activities such as proliferation, migration, apoptosis or inflammation. However, apelin/APJ function in the liver is still under investigation. In the liver, the apelin-APJ system could play an inhibitory role in liver regeneration and promote Fas-induced apoptosis. It may participate in the formation of hepatic fibrosis or cirrhosis, and even cancer. In this review, we summarize the role of the apelin/APJ system in liver disease.

Advances in the treatment of portal hypertension in cirrhosis

Non-selective beta-blockers and handling of esophageal varices has been key elements in the treatment of portal hypertension in recent decades. Liver vein catheterization has been essential in diagnosis and monitoring of portal hypertension, but ongoing needs for noninvasive tools has led to research in areas of both biomarkers, and transient elastography, which displays promising results in discerning clinically significant portal hypertension. Novel research into the areas of hepatic stellate cell function and the dynamic components of portal hypertension has revealed promising areas of treatment modalities, targeting intestinal decontamination, angiogenesis, inflammation and oxidative stress. Future studies may reveal if these initiatives lead to developments of new drugs for treatment of portal hypertension.

The apelin-APJ axis: A novel potential therapeutic target for organ fibrosis

Apelin, an endogenous ligand of the G-protein-coupled receptor APJ, is expressed in a diverse number of organs. The apelin-APJ axis helps to control the processes of pathological and physiological fibrosis, including renal fibrosis, cardiac fibrosis, liver fibrosis and pulmonary fibrosis. However, the role of apelin-APJ in organ fibrosis remains controversial due to conflicting study results. The apelin-APJ axis is a detrimental mechanism which promotes liver fibrosis mainly via up-regulation the expression of collagen-II and platelet-derived growth factor receptor β (PDGFRβ). On the contrary, the apelin-APJ axis is beneficial for renal fibrosis, cardiac fibrosis and pulmonary fibrosis. The apelin-APJ axis alleviates renal fibrosis by restraining the expression of transforming growth factor-β1 (TGF-β1). In addition, the apelin-APJ axis attenuates cardiac fibrosis through multiple pathways. Furthermore, the apelin-APJ axis has beneficial effects on experimental bronchopulmonary dysplasia (BPD) and acute respiratory distress syndrome (ARDS) which suggest the apelin-APJ axis potentially alleviates pulmonary fibrosis. In this article, we review the controversies associated with apelin-APJ in organ fibrosis and introduce the drugs that target apelin-APJ. We conclude that future studies should place more emphasis on the relationship among apelin isoforms, APJ receptor subtypes and organ fibrosis. The apelin-APJ axis will be a potential therapeutic target and those drugs targeted for apelin-APJ may constitute a novel therapeutic strategy for renal fibrosis, cardiac fibrosis, liver fibrosis and pulmonary fibrosis.